The avayab199.xml settings file it gets from the system includes the IP Office systems IP address as the name for the SIP user account used for registration.
I know this as I had a big argument with with the developers during the field trials about this. That value doesn't need to be set in the settings file, ie. they could have left it blank. When that's the case, the phone defaults to showing the extension number which is much better (and if you want you can set it to whatever you need and it won't then get overwritten when the phone restarts).
If its a real problem for you, the only workaround at the momement is to create your own avayab199.xml file rather than use the auto-generated one. But that then becomes something you have to remember you've done and to maintain through upgrades (and for some crazy reason they have managed to change the format of the XML they use in the file 3 times - you can tell that I have a low regard for this particular set of developers ground in the practicallities of real-life system installation and maintenace).
Stuck in a never ending cycle of file copying.
